Pneumatic tool.



G. UHRISTIANSEN. PNEUMATIC TOOL.

APPLICATION FILED MAY 19, 1909.

939,803. Patented N0v.9,1909.

Wzffiesses f KM I also at that end which is served by the other human snares FATENT @FFECE.

CHARLES crinlsrmlvsnu or GELSENKIRCHEN, GERMANY.

PNEUMATIC TOOL.

Application filed. May 19 To all 107mm. it may concrrn:

Be. it known that 'l. (n.uzucs CHRISTIAN- srx. a citizen of the (le -man lhnpire. residing at (hdsenlrirchcn. in the Kingdom of Prussia. (lei-man lllillllltkllilYl) invented new and useful ln'iprm'ements in Pneumatic Tools. o'l which the following is a specificattOll.

This invention relates to improvements in valve gears for pneumatic tools, such as rock drills and the like. And the object. of the improvements is to improvcthe function and construction of apparatus of this class. For this purpose, the Working cylinder is provided at each end with an independent admission valve, and each of the valves is controlled by the pressure of the fluid within the cylinder not only at its adjacent end, but

valve; in this manner the dead space is reduced to a minimum.

The invention also consists in providing reliable means for starting the apparatus.

The invention further consists in so constructing the valves and their controlling means. that the pressure l'lnid acts by expansion within the cylinder. and that the expansion and the charge of the pressure fluid can be regulated, which regulation, in the preferred form of the apparatus, can be offected in such a way, that the charge and the expansion is ditl'orcnt on each side of the piston.

For the purpo e of explaining the invention, an example embodying the same has been shown in the accompanying drawing, in which the same letters of reference have been used in all the views to indicate corresponding parts. r

In said drawing,-F1gure 1 is a. longitu dinal section of the cylinder of a rock drill embodying the invention. Fig. 2 is a vertical cross-section taken on the line A-A of Fig. l. Fig. 3 is a vertical longitudinal section showing on an enlarged scale, a modification of the valve permitting; expansion of the pressure fluid, and Fig. 4- is a similar longitudinal section of a valve showing a modification of the construction of the valve and in combination therewith means for adjusting the pressure on both sides of the valve in order to regulate the charge or the cylinder.

Specification of Letters Patent.

Referring to the example illustrated in the drawing, a is the Working cylinder, Z) the reciprocating piston, c and (Z the valves provided one at each end of the cylinder and Patented Nov. 9, 190%.

. 1909. Serial No. 497.112.

connected with pistons 1" and Il and reciprocating within valve chambers and I]? re spectivcly. The said valves and (Z are adapted to control the hilt" ports 0 and 7 respectively. The pressure iiuid, for exa1nple compressed air. is admin-l to the valve chambers and (1 through a tubular stud g and passages ii and i. The valve pistons are guided in suitable cylirulrical bores in the casting of the cylinder n, which bores are closed in an air tight manner by store *s I; and Z. The space between the screw k and the piston communicates by passage in with thatend of the cylinder which is served by valve 61, and the space between screw Z and piston d, communicates by passage 11- with that end of the cylinder which is served by valve 0; vthe passages m and n are of small cross section. The exhaust; ports are indicated at 0 and p.

The operation of the apparatus is as follows: Assuming that the valve 0 is raise from its seat and the valve d is closed, the pressure fluid flows through the port e into that part of the cylinder (14 which is at the rear of the piston b. Thereby the piston is thrown to the right in Fig. 1 and in the direction of the arrow shown. In the position of the parts shown in the figure, the piston b has already passed over the exhaust so as to close the same. Therefore, the fluid at the front side of the piston is compressed. This compression is transmitted, through the channel m, to the space above the piston 0, so that the pressure on said piston is gradually increased. As soon as the piston 1) uncovers the exhaust 0, and the pressure at the rear of said piston is decreased. the valve c is forced on its seat by the pressure bearing on its piston. 0 It will readily be understood, that in this case there is no expansion of the working fluid within the cylinder (1.

As both valves are operated independently of each other, it. may'l'iappen, when starting the apparatus, that both valves are in their closing positions, so that the pressure fluid can not flow into the cylinder and therefore the apparatus can not be started. Therefore,

means. are provided, whereby one of the valves may be slightly raised from its seat. In the example illustrated in Figs. 1 and 2. the said means consists of a pin 9 having a conical pointv and extending through the casting of the cylinder (6. A pin of this construt-lion may be provided for one of the valves only or tor both oi them. By taming;

the pin inward against the action of a ferent pressures in such a way for instance,

spring 7 by means of a hammer or in a similar way, the conical front end of the pin may engage a beveled shoulder provided at the lower-side of the piston or (P, so that the valve 0 or (Z is raised from its seat.

In the modification shown in Fig. the valves 0 and (l and the devices that control them are constructed, that the pressure fluid is caused to expand within the working cylinder, so that the etlicicncy of the appara-' tus is increased. For this purpose, the valves are so controlled by the pressure fluid, that a smaller pressure is required for closing the valves, than in the example described with reference to Figs. 1 and 2. Therefore the said valves will be forced downward on their seats before the piston I) has uncovered the port .0 or 7'). In the construction shown the valve piston c is guided within a central bore of a screw .9, and it is made integral with a piston rod 0 extending through a plate a providing an air tight closure for the bore of the screw 8. The chamber provided above the piston c communicates through a channel in with that end of the cylinder (1 which is served by valve (Z, and the space below the said valve piston communicates with the atmosphere through a channel 6. Therefore the pressure on the upper side of the valve piston is equal to that at the other end of the cylinder, and the lower side of the valve piston is under atmospheric pressure, so that a comparatively small compression within the cylinder a is surhcient to force the valve on its seat, and the said valve is closed, before the exhaust port of the adjacent cylinder end has been opened; expansion of the pressure fluid therefore occurs during a part B of the stroke of the piston. Upon the return stroke of the piston, a considerable compression of the pressure fluid is necessary to open the valve, because even during the expansion of the fluid at the other end of the cylinder :1 pressure is exerted on the upper side of the valve piston, and also because after the/be gim'iing of the exhaust at the other end of the cylinder, that is after the pressure on the upper and lower sides of the valve piston is balanced, the valve 0 itself is under the pressure of the pressure fluid through the chan-.

nel /z In order to 'vary the pressure on the valve which depends on the li'l'lcrence of the pres sure exerted on the upper and lower sides of the valve piston, and thereby to adjust, the compression of the lluid at the other side of the cylinder piston required for closing the valve, and the position of the working piston in which expansion begins, the chambers above and below the valve piston are shown, in Fig. L, to be connected wit h each other by a channel a adapted to be closed or partly closed by a regulating screw 2:.

The valves 0 and d can be adjusted to difthatupon the forward stroke, that is at the rear of the piston, the expansion is smaller than upon the return stroke, that is at the front side of the piston.

The difference of the pressures exerted on the upper and lower sides of the Valve piston can also be adjusted by partly obstructing the channel in (or a), or the channel 2? for which purpose a throttling screw may be provided, by which the fluid flowing through the said channels is throttled. Also in this case the valves at the front and rear endsof the cylinder a can be regulated in such a way, that thecxpansion and the charge are different on the front and rear sides of the piston. i

The difference of operation of the valves can also be eltected byconstructing the valves, and particularly the valve pistons, of different dimensions.

I claim:

1. A pneumatic tool comprising a. cylinder, a valve at each end for the admission of air thereto, means whereby the pressure of I the compressed air acting directly on each valve serves to open 11; in its turn, and means .whereby the pressure of the compressed air at each end of the cylinder closes the valve at the opposite end.

2. A pneumatic tool comprising a cylinder, a lateral valve chamber at each end having direct communication with the cylinder for the admission of compressed air thereto, a valve in each valve chamber and a communicating passage between the outer portion of each lateral valve chamber and the opposite end of the cylinder.

3. A pneumatic tool comprising a cylinder, a lateral valve chamber at each end thereof, a port leading directly'from each valve chamber into the cylinder for the passage of compressed air thereto, a valve in each-valve chamber, an entrance for compressed air, a passage leading therefrom to each valve chamber, and a passage from the outer portion of each lateral valve chamber to the opposite end of the cylinder.

4. In a pneumatic tool, the combination a chambers which are closed at both ends, a

passage for each of said chambers connecting the same with the cylinder at the other end thereof, and passages connecting the other end of each of said chambers with the atmosphere.

5. in a pneumatic tool, the combination with a cylinder, and a piston rcciprocatin therein, of admission valves one for each on of the cylinder, pistons connected with each of said valves and reciprocating within chambers which are-closed at both ends, a

ceases passage for each of said chambers connecting the same with the cylinder at the other end thereof, passages connecting the other end of each of said chambers with the atmosphere, passages connecting both sides of each of said chambers, and means to regulate the cross-sectional area of each of said passages.

6. In a pneumatic tool, the combination with a cylinder, and a piston reciprocating therein, of admission valves one for each end at the c lin ler, connections between each of said Va v nd the cylinder whereby the pressure within the cylinder at that end which is served by the one valve is trans- 15 mitted to the other valve, and a pin extending through the casting of said cylinder and adapted to raise one of said valves from its seat.

In witness whereof I have hereunto set my 20 hand in presence of two Witnesses.

CHARLES OHRISTIANSEN.

Witnesses:

HENRY HAsPEn, WQLDEMAP. HAUPT. 

